Device for extracting a liquid out of a tube of great length

Abstract

Device for extracting a liquid out of a tube of great length closed at one of its ends in case a communication between the closed end and a source of a substitution fluid should be difficult to establish, the device includes a mobile member provided with a body connected to a supporting surface apparatus, a piston whose cross-section is adapted to the inner cross-section of the tube controlled valve means allowing for the running of the mobile member along the tube and means in the body for providing a substitution fluid such as liquified gas bottles or substances which provide a great volume of gas when combusted. Such a device is useful for example for emptying tube when production tests are conducted in oil wells,.

I claim: 
     
       1. A device for evacuating fluids out of a tube of great length closed at one first end and open at an opposite end, said tube being equipped with retractable means for immobilizing the tube in a well; said device comprising a mobile element the displacement of which towards the open end of the tube ejects the fluids outwardly and motor means for displacing the mobile element, an electric carrying cable for permanently connecting the mobile element with a surface installation, closing means which can be remotely controlled through said electric carrying cable in order to separate portions of the well on either side of the mobile element, means for measuring the pressure prevailing in the well on either side of the mobile element, means for generating a substitution gas on the mobile element and a lifting device connected to the cable for displacing the mobile element towards the open end at a velocity adapted to the outflow of gas released by the gas generating means. 
     
     
       2. A device as claimed in claim 1, wherein the means for generating the substitution gas comprise a volume of a substance for generating a gas by combustion. 
     
     
       3. A device as claimed in claim 2, wherein the substitution means for generating the gas comprise a cartridge containing a pyrotechnic substance and control means for triggering ignition thereof through the electric carrying cable. 
     
     
       4. A device as claimed in any one of claims 1 to 3, wherein the mobile element comprises an elongated body having a piston of a cross-section adapted to conform to an inner cross-section of the tube, said elongated body passing across said piston and being fitted with a first end connected to the lifting device and with a second end open below said piston, the body further having a chamber for containing a combustible substance comprising the gas generating means. 
     
     
       5. A device as claimed in claim 1, wherein the mobile element further comprises at least one set of cups placed in such a way that the cups closely press against said tube and form a piston when the mobile element is displaced towards the open end. 
     
     
       6. A device as claimed in claim 5, wherein each set of cups comprises multiple deformable lips. 
     
     
       7. A device as claimed in claim 5 wherein each set of cups is adapted for forming a piston for tube portions of different cross-sections. 
     
     
       8. A device as claimed in claim 5, wherein the mobile element comprises several sets of cups stepped along the body with a sufficient distance between one another so that at least one set is always in contact with the wall of the tube, whatever the cross inequalities of the tube may be. 
     
     
       9. A device as claimed in claim 1, wherein said retractable means comprise a packer with an inflatable hall. 
     
     
       10. A device as claimed in claim 1, wherein the means for generating a substitution fluid comprise liquefied gas bottles. 
     
     
       11. A method for evacuating fluids out of a tube of great length closed at one first end and open at an opposite end, said tube being equipped with means for immobilizing the tube within a well, said method comprising directing the mobile unit downwardly into the tube towards the closed end, said mobile element being connected to a lifting means placed on a side of the open end of the tube by a cable, and said mobile element having means for forming a piston as the element is displaced towards the open end of the tube; forming a volume of gas between the mobile element and the closed end of the tube; and exerting a traction on the cable at a velocity proportionate to a flow of the formed gas, so that the difference of pressure on either side of the mobile element remains within determined limits.